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Dressed in a heavy winter parka with hood and scarf, Sarala Thapa, left, is followed by her mother Purnima Rai, center, and father M.B. Rai, right, as the Cherry Hill, New Jersey residents return to their car after taking a photo at he State Capitol with Sara's husband, Amrit Thapa, on a Baton Rouge visit with Amrit's friend Bijay Risal, a Baton Rouge General Medical Center physician. The ttemperature was dropping Friday, afternoon, Jan. 6, 2017, and was at 36 degrees by 1 p.m. They were surprised by such cold weather this far south, they said. The Winter Weather Advisory was earlier in the day expandeded into the Baton Rouge area.

ADVOCATE STAFF PHOTO BY TRAVIS SPRADLING

Forecasters upgraded winter weather advisories across southeast Louisiana on Sunday ahead of an "arctic cold front" approaching the area. 

The Baton Rouge area is under a hard freeze warning from 9 p.m. Sunday to noon Monday. Temperatures are expected to be at or below 25 degrees for six to eight hours or longer, according to the National Weather Service.

A wind chill advisory is also in effect for the area from midnight Sunday to 10 a.m. Monday. Wind chill values of 5 to 15 degrees are expected in the area along and north of the I-10/I-12 corridor.   

Parishes in the hard freeze warning and wind chill advisory include Pointe Coupee, West Feliciana, East Feliciana, St. Helena, St. Tammany, Iberville, West Baton Rouge, East Baton Rouge, Ascension, Livingston and Tangipahoa.

In the New Orleans area, a freeze warning is in effect from midnight Sunday to 11 a.m. Monday. Temperatures are expected to drop to 26 to 32 degrees.

A freeze watch has been issued for all of southeast Louisiana for Monday night, as temperatures are expected to drop even further.

The National Weather Service urged residents to check on the elderly, use caution with portable heaters and keep pets indoors or in a warm, dry shelter. Outdoor pipes should be covered to prevent freezing and possible bursting.

A prolonged period of colder-than-average weather is expected to remain for much of the deep south until Friday, NWS said. 

“The whole week is going to be very, very cold,” said Phil Grigsby, a meteorologist from the National Weather Service in New Orleans.

The coldest night for Baton Rouge is anticipated to be Tuesday, when Grigsby said the temperature could fall as low as 17 degrees, two degrees lower than the record for Jan. 2, which was set at 19 degrees in 1928.

Grigsby said temperatures will start dropping New Year's Eve when a cold front follows rains that roll through on Sunday afternoon and evening. But the real freeze isn’t supposed to set in until after the stroke of midnight.

The cold will let up a little on Wednesday and Thursday nights, with low temperatures in the 20s, Grigsby said.

Protected by the warming effects of Lake Pontchartrain, New Orleans should see a low temperature of 24 to 25 degrees on Monday night, Grigsby said. After that, nighttime temperatures will creep slowly up toward 30 degrees on Thursday night. Daytime temperatures there will be about the same as in Baton Rouge.

The four-day cold period is anticipated to be the longest enduring cold event since January 2010.

The Associated Press contributed to this report